extensions: Abstract out install delay strategy

chrome/browser/extensions/shared_module_service.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_SHARED_MODULE_SERVICE_H_
 #define CHROME_BROWSER_EXTENSIONS_SHARED_MODULE_SERVICE_H_
 
 #include <list>
 
 #include "base/macros.h"
 #include "base/scoped_observer.h"
+#include "chrome/browser/extensions/install_gate.h"
 #include "extensions/browser/extension_registry_observer.h"
 #include "extensions/common/manifest_handlers/shared_module_info.h"
 
 namespace content {
 class BrowserContext;
 }
 
 namespace extensions {
 class Extension;
 class ExtensionSet;
 class ExtensionRegistry;
 
-class SharedModuleService : public ExtensionRegistryObserver {
+class SharedModuleService : public ExtensionRegistryObserver,
+                            public InstallGate {
  public:
   enum ImportStatus {
     // No imports needed.
     IMPORT_STATUS_OK,
 
     // Imports are needed, but can be satisfied (i.e., there are missing or
     // outdated imports for a webstore extension).
     IMPORT_STATUS_UNSATISFIED,
 
     // Imports are needed, and can't be satisfied (i.e., missing or outdated
@@ skipping 14 matching lines @@
 
   // Checks an extension's shared module imports to see if they are satisfied.
   // If they are not, this function adds the dependencies to the pending install
   // list if |extension| came from the webstore.
   ImportStatus SatisfyImports(const Extension* extension);
 
   // Returns a set of extensions that import a given extension.
   std::unique_ptr<ExtensionSet> GetDependentExtensions(
       const Extension* extension);
 
+  // InstallGate:
+  Action ShouldDelay(const Extension* extension,
+                     bool install_immediately) override;
+
  private:
   // Uninstall shared modules which are not used by other extensions.
   void PruneSharedModules();
 
   // ExtensionRegistryObserver implementation.
   void OnExtensionInstalled(content::BrowserContext* browser_context,
                             const Extension* extension,
                             bool is_update) override;
   void OnExtensionUninstalled(content::BrowserContext* browser_context,
                               const Extension* extension,
                               extensions::UninstallReason reason) override;
 
   ScopedObserver<ExtensionRegistry, ExtensionRegistryObserver>
       extension_registry_observer_;
 
   // The context associated with this SharedModuleService.
   content::BrowserContext* browser_context_;
 
   DISALLOW_COPY_AND_ASSIGN(SharedModuleService);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_SHARED_MODULE_SERVICE_H_